Tuesday, June 8, 2010

...Intercept?

We had an interesting day yesterday.

After sitting in a park in Kimball, NE for about 4 or 5 hours, we moved north towards Scottsbluff and prepared to deploy on our target storm. At this point we could also see a good number of chasers converging on the area on StormLab (plug for Evan) and I was at least a little concerned about that. We'd already tried to deploy in that area earlier this year and ran up against a poor road network; the addition of more cars pulled over could have made deployments even more difficult. Probe 12 consisted of Lindsay and myself only yesterday, and we pulled over in a parking lot literally next to the Nebraska/Wyoming border on the Wyoming side. We were then sent back into Nebraska to attempt another play on the target storm. It caught up with us again and we were forced to backtrack and continue to move east to get ahead of the storm. At this point DOW6 recorded a decent tornado that was even visible at the lowest tilt of the nearest WSR-88D.

Eventually that storm began dying (because we kill storms) so we had to move back west to go after a new target following immediately behind the first. Our initial concern was that the storm following the first one would be eating the former's dust...literally. If the first storm had eaten up all the good air and then output less desirable air, it would kill the second storm off before it had a chance to produce anything. As we moved back west and then east again (this happens a lot), an interesting turn of events occurred. Operations were about to be called off, teams were making dinner plans amongst themselves, when DOW7 began observing a new area of interest. At the same time, our probes and others began reporting power flashes, a funnel, some debris... and things started getting hectic. Our probes were sent back to 26 to potentially deploy pods along the busy road that was also full of chasers hightailing it away from this unexpected tornado.

Once we got to 26, in the confusion 3 of us moved west towards the storm about half a mile and the others held up at the intersection of 26 and 71, the north-south road DOW7 was deployed on. Josh came over the radio to announce that the tornado was crossing 26 so we wouldn't have an opportunity to deploy pods, but to hurry east (again) to get ahead of it. Unfortunately, the road had a median and 3 of our pod vehicles had to move west towards the "area of interest" before we could get back east.

For Probe 12, this next 30 seconds was very interesting.

I had hopped out to turn on our pod cameras in the back of the truck and when I got back in the vehicle the door ajar light came on. Thinking it was our back door, I hopped out again as other vehicles were fleeing to make sure the back was closed. When I hopped back in, I realized it was my door that was ajar. As I was trying to figure out why, Lindsay moved the vehicle further west to our closest turn-around spot, and we were hit by a very strong wind gust that knocked the antenna on our vehicle off the top and significantly rocked our Dodge Ram. The two vans in our crew were also at the same location, but Probe 12 was the only vehicle with weather instruments.

After the storm became outflow dominant (aka not going to do much from now on), Lindsay and I collected our mesonet data to discover we'd recorded a 50 m/s wind gust at that time. That's over 100 mph. That number is before we subtract our vehicle speed, which was about 30 mph at the time. The people that process the data will do that, and we cannot wait to find out what the post-vehicle moving speed is. The NSSL/PSU mesonets recorded gusts of ~35 m/s with vehicle movement taken out at a nearby location, about 70 mph. These values were recorded while DOW7 was recording a weak tornado a few kilometers southwest of its location.

That all being said, we're not exactly sure of our location. A few of us wonder if we were in the outer circulation of the tornado and will make that our story until the data tell us otherwise. :) More likely is that we were in some very strong outflow as the gust front passed through. Initially Karen said we should have been east of the storm when they sent us that direction so we shouldn't have been near the circulation, but once we explained that a few of us went west instead of east she said, "...Ohhhh"... but still figures we were safely out of the way. Nonetheless, it was a very exciting experience, especially given our not so interesting experiences from the rest of the project. If nothing else I'm happy that our probe was able to add to the other mobile mesonet data along that transect since no one really expected anything to happen at that point, so this case will be interesting to put back together to figure out what happened and how.

2 comments:

  1. I can't see your vehicle location image; it's "401 Authorization Required".

    Can you repost it somewhere that doesn't ask us to log in, please?

    ReplyDelete
  2. I'll have to remove the image, I thought I'd worked around that issue.

    ReplyDelete